JPS60218994A - Color television camera employing radiation-resistant color repeatability compensation circuit - Google Patents

Abstract

PURPOSE:To improve the radiant-ray resistance of a television camera by providing a color repeatability compensation circuit for correcting the deterioration in the color repeatability caused by the dosage rate of radiant rays. CONSTITUTION:If a monitor depresses a button of ''correction selection'' utilized in non-radiant-ray atomosphere, a pulse-shaped correction trigger signal 505 is transmitted to a television camera. A quarter of the number N of scanning lines (normally 512) is set in a counter 501 so as to carry out compensation at the center of an image-pickup tube. The counter 501 counts horizontal synchronizing signals 41, and outputs correction permission signals 506 by delay of a half of a scanning line period after the counted value shows a quarter of the number N. A correction start signal closes a contact point for correction at its rise. A comparator 530 calculates the difference between a composite video signal Sr at the time of light-shielding in the point and a composite video signal So when it is not irradiated at the time of light-shielding, and controls voltages of process amplifiers 6, 76 and 77 of respective chrominance signals.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a color television (hereinafter abbreviated as TV) camera that can be used in a radiation atmosphere.

[Background of the invention]

Radiation-resistant TV, - Prior art related to cameras (1972)
As stated in the Proceedings of the Atomic Energy Society of Japan (C-56) in 2013, it is disclosed that a compensation circuit for deterioration of color reproducibility with respect to integrated dose is useful.

However, it should be recognized that with this technology, the radiation dose rate affects color reproducibility.

[Purpose of the invention]

Therefore, an object of the present invention is to correct the deterioration of color reproducibility depending on the radiation dose rate, thereby eliminating the above-mentioned drawbacks of the conventional technology, and providing a radiation-resistant color TV camera that can be used even in a high dose rate atmosphere. It's about doing.

[Summary of the invention]

The present invention will be explained in detail using FIG. FIG. 1 is a block diagram when the present invention is applied to a color TV camera that uses an image pickup tube as an imaging device and adopts a frequency separation method as a color imaging method. Solid line is color T
Among the constituent blocks of the V camera, conventional ones are shown, and the broken line is the color reproducibility correction circuit 5 of the present invention. In a conventional color TV camera, as the radiation dose rate increases, the composite video signal level also increases as shown in the graph of FIG. FIG. 2 shows the amount of increase in the composite video signal level with respect to the gamma ray dose rate when no light enters the image pickup tube from the outside (during light shielding) in order to extract only the influence of the radiation dose rate. This is due to an increase in dark current in the imaging device and amplifier due to γ-ray irradiation. Therefore, the luminance signal voltage shown in FIG. 2 is called a dark voltage. When the dark voltage increases, the color information of red (6), blue (E3), and green (Q) is compressed, and furthermore, when the dark voltage exceeds the upper limit of the dynamic rotation of each color information, color information is lost.

Therefore, in the present invention, pure silica glass or Ce(
Using a radiation-resistant bipolar element doped with cerium (cerium), the radiation resistance of the entire TV camera is improved, and a brightness signal level compensation circuit is provided to compensate for the increase in brightness signal level due to radiation dose rate. This is further characterized by improving the radiation resistance of the TV right camera.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail based on examples.

First, the outline of a color TV camera and its operation will be explained using FIG. The color TV camera uses its imaging method,
Depending on the number of image pickup tubes, they are classified into three-tube color TV cameras, phase-separated two-tube color TV cameras, and single-frequency separation single-tube color TV cameras. Here, explanation will be given by taking a single-tube color 'I'V camera with wave number separation as an example.

An image of a subject 1 is focused on a photocathode of an image pickup tube 3 by a lens 2. FIG. 3 shows an example of the image pickup tube 3.

The incident light 31 passes through a quartz filter, has color information on a face plate glass 33 on which a striped color filter 37 is mounted, and is imaged onto a target surface 34.

A video signal is extracted from the transparent conductive film 38 by scanning this imaged image from the cathode 35 with a beam beam 36. The position of the electron beam is controlled by horizontal and vertical deflection circuits. Figure 4 shows a striped color filter 37 on the face plate glass.
It is a figure showing a state where it is attached. Figure 5 shows the fourth
The arrow direction view in the AA' sectional view in the figure is shown. The stripe color filters are filters with the same pitch (stripe frequency) of two types: a yellow stripe filter 37 of transparent and yellow (blue does not pass, complementary color of blue) and a cyan stripe filter 372 of cyan (red does not pass, complementary color of red). are intersecting. However, as shown in FIG. 6, the intersection angle is such that the phase of the video signal S1 obtained from the image pickup tube 2 through this filter changes by π/2 for each scanning line. The color information signal modulated at the frequency of this stripe filter becomes only a color information signal by a bandpass filter 71 corresponding to the stripe frequency. Assuming that the congruent scanning signals (Ll and La in FIG. 6) have almost the same color information, the output signals of the cyan and yellow stripe filters, as shown in FIG.
Corresponding to r and Lm, they are a, A, and B, respectively. Since the phase of each stripe filter is shifted by π/2 with respect to scanning lines Ll and L3, scanning line L3 is shifted by π/2.
When added to the scanning line L1 shifted by 2 or -π/2, one color component disappears and the other color component doubles. In the case of Figure 5, π
When advanced by /2, only the cyan side, that is, the red component remains, and the yellow side, that is, the blue component disappears. Conversely, π/2
If the delay is delayed, only the blue component will be present. Such processing is performed by a scanning line delay circuit 72, a ±π/2 phase shifter 73, a red component demodulation circuit 74, and a blue component demodulation circuit 75. The color-separated red component signal and blue component signal are sent to a process amplifier 7.
6.77 each amplified.

On the other hand, the luminance signal and the low frequency component representing the green component are determined as follows. The cyan stripe filter 372 passes 0 green components and 0 blue components. In addition, the yellow stripe filter 371 allows the green component (G and red component (6) to pass through. Therefore, at the intersection of the two layers, the green component 0 passes through. On the other hand, the -red component ( 6) is the first
Since it does not pass through the cyan part of the cyan stripe filter 372, the first cyan stripe filter 37
Obtained only from the transparent part of 2. The blue component (b) is as described in 2.
Since it does not pass through the negative part of the second yellow stripe filter 371, it is obtained only from the transparent part of the second yellow stripe filter. In this way, both the red component (6) and the blue component (B) have been reduced to 1/2 of the original incident light,
(G+1/2R+1/2B) is obtained as a low frequency component of the video signal output which is the output of the low pass filter 81. A luminance signal is then obtained through a luminance signal processing circuit 6 consisting of a process amplifier.

The red component signal, blue component signal, and luminance signal obtained in this manner are converted into an orange-cyan component with high color difference visual acuity, that is, a 1-axis component, and a green to violet component, that is, a Q-axis component with low color difference visual acuity, in a color kneader 80. A composite video signal including the signal is sent to the monitor side.

In FIG. 1, a color reproducibility compensation circuit 5 of the present invention is provided to correct deterioration in color reproducibility due to radiation dose rate.

FIG. 7 is a diagram showing an embodiment of the luminance signal level compensation circuit 5 of the present invention, and is an example applied to a camera having an automatic aperture mechanism 543. FIG. 8 is a timing chart of the main signals in FIG.

The set voltage 8G of the comparator 530 in FIG. 7 indicates the composite video signal level at the time of light shielding without irradiation.

When an observer working in a non-radiation atmosphere presses the correction selection button in order to correct the deterioration of color reproducibility due to the radiation dose rate, a pulsed correction trigger signal 505 is transmitted to the television camera.

This correction trigger signal 505 is latched by a latch circuit 540 and outputs a correction signal 520. The correction signal 520 is
The iris motor 542 is forced into a fully closed state. That is, in order to achieve a light shielding state, the contact point of the relay 544 is changed from a to b. The power supply of 545 is connected to the iris motor so that the iris is fully closed. The correction signal 520 also opens the gate 504.

The synchronization signal generation circuit 4, counter 501, and gate 504 are used to compensate for color reproducibility when the image pickup tube of the camera is at the center. A horizontal synchronizing signal 41 and a vertical synchronizing signal 42 are output from the synchronizing signal generating circuit 4.

The counter 501 is set to a value of N/4 of the number of scans N (usually 512) so that compensation can be made at the center of the image pickup tube. The reason for choosing N/4 instead of N/2 is that normal cameras use an interlaced method, so the first N/2 scans the entire screen, and the remaining N/2 scan each scanning line. This is because it scans the space between. Therefore, the vertical periodic signal 42
, the counter 501 counts the horizontal synchronizing signals 41, and after reaching N/4, the correction permission signal 506 is output with a time delay of 1/2 of the scanning line period.
Output. At that time, if the correction signal 520 is off,
A gate 504 outputs a correction start signal 508 for a certain period of time. The correction start signal closes the correction contact 533 when it rises, and resets the latch circuit 540 when it falls. When the correction contact 533 closes, the comparator 530 calculates the difference between the composite video signal Sr at the time of light shielding and the composite video signal So at the time of light shielding without irradiation, and holds the difference in the signal hold circuit 531. .

The process signal voltage regulator 532 controls the process amplifiers 6 and 6 of each color signal according to the output of the hold circuit until the next correction.
76.77 voltage control. distributor 534.535,
536 distributes the output of the process voltage regulator 532 according to the degree of influence on the composite video signal during light shielding, and controls the voltage of the process amplifiers 6, 76, 'I'l for each color signal. As a result, the output of the process amplifier for each color signal at each light shielding time is lowered, and the deterioration in color reproducibility that occurs depending on the gamma ray dose rate is corrected.

Next, a second embodiment of the present invention will be described using the drawings. FIG. 12 shows a block diagram of a color TV camera using the second embodiment of the color reproducibility correction circuit.

The present invention is a method of correcting the increase in color signal level due to radiation dose rate in each color signal component. FIG. 2 shows the irradiation characteristics of the composite video signal when light is blocked. but,
Even if a signal component is present even when the light is not blocked, the amount of increase in the composite video signal level is the same as when the light is blocked. Therefore, correction is possible if it is performed under the same conditions as when not irradiated. The 10th signal is used as a reference signal for correcting the color reproducibility of each color component.
Use the color pattern shown in the figure. In order to perform the correction accurately, it is necessary to apply the same illuminance to the same place. Therefore, as shown in FIG.
When a color TV camera is installed in a device such as the above, the color pattern is fixed at a standby position, etc., and the color TV camera is pointed at the pan head 101 in the direction of the color pattern, which is the subject 1, and the zoom ratio is set by the lens 2. , adjust focus, etc.

These operations are performed from the console 102 located in a place that is not in a radiation atmosphere. These control signals are transmitted to the color TV camera by cable 103. An example of correcting the red component will be explained. FIG. 7 shows an embodiment of the red component color reproducibility compensation circuit. Consider the blue component and green component in the same way. When the observer selects the color reproducibility correction switch 104 and then selects the red component configuration switch 105, a correction trigger signal 505 and a red component correction trigger signal 507 are transmitted, and these two signals cause the red component color reproducibility trigger signal 50 to be transmitted.
I can do 9. The function of each signal below is the same as that of the first implementation, except that the comparison level 5IIO of the counter 501 and the comparator 530 is the output voltage of the red component process amplifier when viewing the red part of color pattern 1 without illumination. Same as in the example. In the first embodiment, the correction was made at the center of the imaging surface of the image pickup tube 3, that is, at the center of the subject 1, but in the second embodiment,
A counter for the number of scans and a delay time within one scan period are set so that the red part of the color pattern of the object 1 is centered. Assuming that the area occupied by each color component is the same, the number of scans is N/b from FIG. 10, and the delay time is 5/6t, where one scanning time is t.

As described above, color reproducibility can be corrected by correcting the increase in the color component relative to the radiation dose rate for each color component.

[Effect of Enmei]

As explained above, according to the present invention, the glass used for the lens 2 and the image pickup tube 3 is made of pure silica glass or C.
By using radiation-resistant glass doped with e (cerium) and using radiation-resistant bipolar elements in the synchronization signal generation circuit, etc., the radiation resistance of the entire color TV camera is improved, and the radiation resistance is dependent on the radiation dose rate. By providing a color reproducibility compensation circuit for correcting deterioration in color reproducibility, it is possible to provide a color TV camera with further radiation resistance.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an overview of a color TV camera and the insertion position of the color reproducibility compensation circuit of the first embodiment. FIG. 2 is a diagram showing changes in the composite video signal level depending on the radiation dose rate. Figure 3 is a diagram showing an example of an image pickup tube, Figure 4 is a diagram showing a stripe color filter installed on the face plate glass,
FIG. 5 is a diagram showing an arrow view of the AA' cross section in FIG. 4, FIG. 6 is a diagram showing the principle of hue signal separation in a single frequency separation method, and FIG. 8 is a diagram showing the timing chart of the main signals in FIG. 7. FIG. 9 is a diagram showing the insertion position of the color reproducibility compensation circuit of the second embodiment. Fig. 10 is a diagram showing a color pattern, Fig. 11 is a conceptual diagram of color reproducibility compensation operation, and Fig. 12 is a diagram showing a color pattern.
The figure shows a color reproducibility compensation circuit according to a second embodiment. 2... Lens, 3... Image pickup tube, 4... Synchronization signal generation circuit, 6... Green component process amplifier, 32... Crystal filter, 33... Face plate glass, 36... Electronic Beam, 37... Stripe color pattern, 38... Transparent conductive plate, 5... Color reproducibility compensation circuit in the first embodiment, 51... Red component color reproduction in the second embodiment 52... Blue component color reproducibility compensation circuit in the second embodiment, 53... Green component color reproducibility compensation circuit in the second embodiment, 71... Bandpass filter, 72...
・Scanning line delay circuit, 73...±π/2 transfer path, 74・
...Red component demodulation circuit, 75...Blue component demodulation circuit, 76
...Red component process amplifier, 77...Blue component process amplifier, 80...Cassie encoder, 102...
console. Figure 2 Dose book (outside) Figure 9 7 6 Figure 7 Male Figure 8 q Figure 70 Figure 1? figure

Claims (1)

[Claims] 1. A color TV using a radiation-resistant color reproducibility compensation circuit, characterized in that a color reproducibility compensation circuit for correcting deterioration of color reproducibility due to radiation dose rate is provided in a color +11v camera. camera. 2. In claim 1, the amount of correction of the color reproducibility compensation circuit is determined based on the difference between the composite video signal level when light is shielded without irradiation and the composite video signal level when light is shielded under a certain radiation dose rate. A color TV camera using a radiation-resistant color reproducibility compensation circuit characterized by: 3. In claim 1, the difference between the color signal level before irradiation and the color signal level under the current radiation dose rate is determined for each color component, and the correction amount of the color reproducibility compensation circuit is determined from these values. A color TV camera using a radiation-resistant color reproducibility compensation circuit.